:root{
  --paper:#E9EBEE;
  --surface:#FFFFFF;
  --ink:#1B2733;
  --muted:#5C6B7A;
  --line:#C9D0D8;
  --brass:#A8792C;
  --ok:#2F6B4F;
  --warn:#9B2C2C;
  --sans:-apple-system,BlinkMacSystemFont,"Hiragino Kaku Gothic ProN","Yu Gothic Medium","Yu Gothic","Noto Sans JP",Meiryo,sans-serif;
}
*{box-sizing:border-box}
body{
  margin:0;background:var(--paper);color:var(--ink);
  font-family:var(--sans);font-size:17px;line-height:1.9;
  -webkit-font-smoothing:antialiased;
}
img,svg{max-width:100%}
a{color:var(--ink)}
:focus-visible{outline:2px solid var(--brass);outline-offset:3px}

.wrap{max-width:720px;margin:0 auto;padding:0 20px}
section{padding:56px 0}
section + section{border-top:1px solid var(--line)}

h1{font-size:36px;line-height:1.45;font-weight:700;letter-spacing:.01em;margin:0 0 20px}
h2{font-size:23px;font-weight:700;margin:0 0 20px}
h3{font-size:18px;font-weight:700;margin:0 0 6px}
p{margin:0 0 16px}
.lead{font-size:18px;color:var(--muted)}
.small{font-size:15px;color:var(--muted);line-height:1.8}

.topbar{
  background:var(--surface);border-bottom:1px solid var(--line);
  padding:12px 0;font-size:15px;
}
.topbar .wrap{display:flex;align-items:center;gap:16px}
.topbar .brand{font-weight:700;margin-right:auto;line-height:1.4}
.topbar .tagline{display:block;font-weight:400;font-size:13px;color:var(--muted)}
.topbar a{color:var(--muted);text-decoration:none}
.topbar a:hover{color:var(--ink)}

.hero{background:var(--surface);padding:64px 0 56px}
.cta{
  display:inline-block;background:var(--ink);color:#fff;text-decoration:none;
  font-size:18px;font-weight:700;padding:16px 32px;border-radius:2px;
}
.cta:hover{background:#0F1922}
.cta-note{font-size:15px;color:var(--muted);margin-top:12px}
.cta-line{display:flex;align-items:center;gap:20px;flex-wrap:wrap}
.cta-sub{color:var(--muted);text-decoration:underline;text-underline-offset:4px}

.figure{background:var(--surface);border:1px solid var(--line);padding:24px 20px;margin:0 0 12px}
figcaption{font-size:15px;color:var(--muted);line-height:1.8}

.points{display:grid;gap:28px}
.point{display:grid;grid-template-columns:auto 1fr;gap:16px;align-items:start}
.point .mark{
  width:34px;height:34px;border:1px solid var(--brass);color:var(--brass);
  display:grid;place-items:center;font-weight:700;font-size:16px;border-radius:50%;
}
.point p{margin:0;color:var(--muted)}

.steps{counter-reset:step;list-style:none;margin:0;padding:0;display:grid;gap:24px}
.steps li{counter-increment:step;display:grid;grid-template-columns:auto 1fr;gap:16px}
.steps li::before{
  content:counter(step);
  width:34px;height:34px;background:var(--ink);color:#fff;
  display:grid;place-items:center;font-weight:700;font-size:16px;border-radius:50%;
}
.steps p{margin:0;color:var(--muted)}

.cols{display:grid;grid-template-columns:1fr 1fr;gap:28px}
.cols h3{padding-bottom:8px;border-bottom:2px solid currentColor}
.can h3{color:var(--ok)}
.cant h3{color:var(--warn)}
.cols ul{margin:0;padding-left:1.2em;color:var(--muted)}
.cols li{margin-bottom:10px}

.qa{border-top:1px solid var(--line)}
.qa details{border-bottom:1px solid var(--line);padding:16px 0}
.qa summary{font-weight:700;cursor:pointer;list-style:none}
.qa summary::-webkit-details-marker{display:none}
.qa summary::before{content:"＋";color:var(--brass);margin-right:10px;font-weight:700}
.qa details[open] summary::before{content:"−"}
.qa p{margin:12px 0 0;color:var(--muted)}

.provider{background:var(--surface)}
footer{background:var(--ink);color:#AEBAC6;padding:32px 0;font-size:15px;line-height:1.9}
footer a{color:#fff}
footer .links{display:flex;gap:18px;flex-wrap:wrap;margin-bottom:12px}
footer .footer-brand{margin:0 0 12px}
footer .footer-logo{display:inline-block;background:#fff;padding:10px 14px;border-radius:3px;line-height:0}
footer .footer-logo img{width:150px;height:auto;display:block}
footer .footer-credit{margin:0;font-size:14px;color:#8A97A5}

.spec{
  background:var(--surface);border:1px solid var(--line);
  padding:14px 16px;margin:0 0 16px;overflow-x:auto;
  font-family:"SFMono-Regular",Consolas,"Noto Sans Mono",monospace;
  font-size:13px;line-height:1.8;color:var(--ink);
}
code{
  font-family:"SFMono-Regular",Consolas,"Noto Sans Mono",monospace;
  font-size:.92em;background:var(--surface);
  border:1px solid var(--line);padding:.1em .4em;border-radius:2px;
}
#continuity h3{margin-top:32px}
#continuity h3:first-of-type{margin-top:24px}

.doc h2{margin-top:36px}
.doc ol,.doc ul{color:var(--muted);padding-left:1.4em}
.doc li{margin-bottom:8px}

@media (max-width:620px){
  h1{font-size:29px}
  section{padding:40px 0}
  .hero{padding:44px 0 40px}
  .cols{grid-template-columns:1fr;gap:24px}
  .cta{display:block;text-align:center}
  .cta-line{display:block}
  .cta-sub{display:inline-block;margin-top:14px}
}

/* ── パソコン向け：見出しを左の柱に出し、本文は読みやすい幅に保つ ── */
@media (min-width:980px){
  .wrap{max-width:1120px;padding:0 48px}

  section > .wrap{
    display:grid;
    grid-template-columns:168px minmax(0,1fr);
    column-gap:44px;
    align-items:start;
  }
  /* 長い文章だけは読みやすい幅で止める */
  section > .wrap > p,
  section > .wrap > ol,
  section > .wrap > ul{max-width:44em}
  section > .wrap > *{grid-column:2}
  section > .wrap > h2{
    grid-column:1;grid-row:1;margin:0;
    position:sticky;top:40px;
    font-size:21px;line-height:1.6;
    padding-top:4px;border-top:2px solid var(--brass);
  }

  /* 規約ページは見出しが多いので、通常の1段組みのまま */
  section.doc > .wrap{display:block;max-width:800px}

  .hero{padding:96px 0 80px}
  .hero .wrap{max-width:1120px}
  .hero h1{font-size:48px;max-width:20em}
  .hero .lead{max-width:46em;font-size:19px}

  /* 仕組みは3つ並べる */
  .points{grid-template-columns:repeat(3,1fr);gap:36px}
  .point{grid-template-columns:1fr;gap:12px}

  /* 使い方は2列 */
  .steps{grid-template-columns:1fr 1fr;column-gap:44px;row-gap:32px}

  /* 安全性の2列は横幅をいっぱいに使う */
  #safety > .wrap{grid-template-columns:168px minmax(0,1fr)}
  .cols{gap:56px}

  /* 図はやや大きく */
  .figure{padding:32px 28px}
  figcaption{max-width:60em}

  /* よくある質問は行間に余裕を持たせる */
  .qa details{padding:20px 0}
}

@media (min-width:1280px){
  .wrap{max-width:1200px}
  section > .wrap{grid-template-columns:190px minmax(0,1fr);column-gap:56px}
  #safety > .wrap{grid-template-columns:190px minmax(0,1fr)}
}